I always liked a knife with a distinct point. With the point, I can make entry cuts and cuts around eyes.
I would suggest a 4" fillet knife. Nice pointed tip and blade long enough to make cuts through thick butt fur.
Like Goose said, you may go through a few knives until you find what works for you.
I have skun and put up fur with many guys over the years. The wide variety of knives I've seen used is crazy, from Marine KABAR to a single razor blade held between finger and thumb. Not trying to say that in a bad way, shows how we can adapt and use any tool, I guess.
So, I feel a bit off when recommending knives, boots, rain gear, ammo and such.
Here's the knives I use for skun'n:
Top- Dexter Russell Bolens, 2 1/2" blade
Second- Finland fillet knife, 4" blade (fast becoming my favorite and the one I always reach for)
Third- Ole favorite, no name, been with me a long time, 2 3/4" blade
Bottom- Ole sharpening stone
Here's a Mink pelting knife. Razor blade. I just couldn't get the hang of this knife, and it's laid around for years without being used.
Martor #360, German made.